Electrolytic capacitor

ABSTRACT

Disclosed is an electrolytic capacitor including: a capacitor element including a pair of electrodes; an electrolyte interposed between the pair of electrodes; a pair of leads electrically connected to the pair of electrodes, respectively; a case in which the capacitor element and the electrolyte are accommodated, and that has an opening; a sealing member that seals the opening, and has a pair of insertion holes for leading out the leads; an insulating plate having a pair of through holes for leading out the leads; and a resin member filled between the sealing member and the insulating plate, wherein the insulating plate has a resin bonding surface that abuts against the resin member, and a mounting surface opposed to the resin bonding surface, and includes at least one protrusion or recess on the resin bonding surface.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/643,455, filed on Sep. 4, 2020, which is the U.S. National Phaseunder 35 U.S.C. § 371 of International Patent Application No.PCT/JP2018/032478, filed on Aug. 31, 2018, which in turn claims thebenefit of Japanese Patent Application No. 2017-167592, filed on Aug.31, 2017, and Japanese Patent Application No. 2017-167593, filed on Aug.31, 2017, the entire disclosures of which Applications are incorporatedby reference herein.

TECHNICAL FIELD

The present invention relates to an electrolytic capacitor, andparticularly relates to an electrolytic capacitor including a resinmember between a sealing member and a base plate. Note that the presentapplication is based upon and claims the benefit of priority from thecorresponding Japanese Patent Application Nos. 2017-167592 and2017-167593 both filed on Aug. 31, 2017, the entire contents of whichare incorporated herein by reference.

BACKGROUND ART

In general, due to their high reliability, electrolytic capacitors arebeing widely used, not only for consumer devices, but also as a part ofvehicle-mounted circuits that are used under severe conditions. Inparticular, electrolytic capacitors used in an environment with hightemperature and humidity, such as in an engine, are required to ensureoperations, for example, at about 150° C. for the period of time on theorder of several thousands of hours.

A typical electrolytic capacitor includes a capacitor element includinga pair of electrodes; an electrolyte interposed therebetween; a case inwhich the capacitor element and the electrolyte are accommodate, andthat has an opening; a sealing member that is made of butyl rubber andseals the opening; a base plate having a pair of through holes; and apair of leads that are electrically connected to the pair of electrodes,respectively, and extend from the through holes. Voids are formedbetween the sealing member and the insulating plate, and the sealingmember is substantially exposed to outside air (environment with hightemperature and humidity).

In general, the butyl rubber contained in the sealing member is ahigh-molecular weight polymer, which, upon exposure to air (oxygen) orwater (moisture), undergoes oxidation degradation, causing the molecularchains thereof to break down and the molecular weight thereof todecrease. In addition, the sealing member contains carbon, and, whenexposed to an environment with high temperature and humidity, undergoesa reduction in volume and becomes susceptible to cracking, and thecarbon molecules contained in the sealing member are bound together toincrease the conductivity of the sealing member, thus generating aleakage current between the pair of electrodes, which may impair thefunction of the electrolytic capacitor.

For example, the electrolytic capacitor described in PTL 1 includes abase plate including, at the center thereof, a depressed portion that isdepressed so as to receive a lower portion of a capacitor body; and thecapacitor body in which a capacitor element including an electrolyte isstored in a tubular metal case that is closed at the top, the loweropening of metal case is sealed by a sealing member, a pair of electrodeterminals that are lead out downward from the capacitor elementpenetrate the sealing member so as to extend downward, and the electrodeterminals further penetrate the base plate, and are bent along thebottom surface of the base plate in a direction away from each other.The capacitor body is fixed to the base plate with an adhesive injectedinto a recess that is provided in a non-depressed portion located aroundthe depressed portion of the base plate and that is open at least on thedepressed portion side.

The adhesive described in PTL 1 is injected from the recess of thenon-depressed portion located around the depressed portion of the baseplate, and serves to reliably fix the base plate and the capacitor body.

Additionally, for example, the chip-type capacitor described in PTL 2seals the opening of a packaging case by a sealing member made of anelastic rubber or the like, and the so-called curling, in which theopening of the packaging case and a side surface located near theopening are drawn in, is further performed to seal the interior of thepackaging case. PTL 2 proposes that, to an end face of a capacitorincluding a plurality of lead wires all guided out from the end face, aninsulating plate having apertures at positions corresponding to the leadwires is abutted against, and the lead wires that are passed through theapertures so as to protrude from the insulating plate are bent along anend face of the insulating plate, and a resin layer is formed in a gapbetween the end face of the capacitor and the insulating plate, and gapsbetween the lead wires of the capacitor and the corresponding aperturesof the insulating plate.

The resin layer described in PTL 2 is formed in the gap between the endface of the capacitor and the insulating plate, and the gaps between thelead wires of the capacitor and the apertures of the insulating plate,and severs to prevent water or a washing solvent from entering from thespaces between the lead wires, to which stress has been applied by thebending process, and the apertures of the insulating plate, thusrealizing high reliability.

CITATION LIST Patent Literature

-   [PTL 1] Japanese Laid-Open Patent Publication No. 2000-269081-   [PTL 2] Japanese Laid-Open Patent Publication No. H2-194614

SUMMARY OF INVENTION Technical Problem

However, although the adhesive described in PTL 1 is injected from therecess of the non-depressed portion located around the depressed portionof the base plate, and assists the fixing of the capacitor body to thebase plate, the rubber sealing member attached to the opening of thepackaging case is easily exposed, during use, to air (oxygen) and/orwater (moisture) entering the packaging case via holes provided in thebase plate and is very susceptible to oxidation. When oxidized, thesealing member undergoes a reduction in volume and becomes susceptibleto cracking, and the molecular weight of the rubber that forms thesealing member is reduced, and the carbon molecules contained in thesealing member are bound together, so that a leakage current tends to begenerated between the pair of electrode terminals.

Since the resin layer described in PTL 2 is formed in the gap betweenthe end face of the capacitor and the insulating plate, and the gapsbetween the lead wires of the capacitor and the apertures of theinsulating plate, it can be considered that the sealing member, which issimilarly made of an elastic rubber or the like, will be protected fromair (oxygen) and/or water (water vapor) entering from the outside.However, the resin layer is made of epoxy resin or silicone resin, andhas a coefficient of thermal expansion significantly different from thatof the sealing member made of an elastic rubber. Accordingly, the resinlayer may be detached from the sealing member by heat shock as a resultof a long-term use, resulting in formation of voids in the interfacetherebetween. When voids are formed between the resin layer and thesealing member, the sealing member made of an elastic rubber issimilarly exposed to air (oxygen) and/or water (moisture) entering fromthe outside, then undergoes oxidation, and becomes susceptible tocracking. Furthermore, a leakage current may be generated between thepair of electrode terminals via water that has been accumulated in thevoids.

Therefore, it is an object of an aspect of the present invention toprovide an electrolytic capacitor that realizes high reliability over along period of time even under severe operating conditions, by filling aresin member between a sealing member and an insulating plate (baseplate) to enhance the adhesion between the resin member and the sealingmember, thus reliably blocking air (oxygen) and/or water (water vapor)entering from the outside to prevent oxidation degradation of thesealing member.

Solution to Problem

An electrolytic capacitor according to an aspect of the presentinvention includes a capacitor element including a pair of electrodes;an electrolyte interposed between the pair of electrodes; a pair ofleads electrically connected to the pair of electrodes, respectively; acase in which the capacitor element and the electrolyte areaccommodated, and that has an opening; a sealing member that seals theopening, and has a pair of insertion holes for leading out the leads; aninsulating plate having a pair of through holes for leading out theleads; and a resin member filled between the sealing member and theinsulating plate, wherein the insulating plate has a resin bondingsurface that abuts against the resin member, and a mounting surfaceopposed to the resin bonding surface, and includes at least oneprotrusion or recess on the resin bonding surface.

Advantageous Effects of Invention

With the electrolytic capacitor according to an aspect of the presentinvention, it is possible to realize high reliability over a long periodof time even under severe operating conditions, by filling a resinmember between a sealing member and an insulating plate (base plate) toenhance the adhesion between the resin member and the sealing member,thus reliably blocking air (oxygen) and/or water (water vapor) enteringfrom the outside to prevent oxidation degradation of the sealing member.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a partial broken-away perspective view partially showing theinterior of an electrolytic capacitor according to a first embodiment ofthe present invention.

FIGS. 2(a) to 2(c) show a plan view, a bottom view, and a side view,respectively, of the electrolytic capacitor shown in FIG. 1 .

FIG. 3(a) is a cross-sectional view of the electrolytic capacitor, takenalong the line III-III in FIG. 2(a), and FIG. 3(b) is a plan view of thebase plate shown in FIG. 3(a), as viewed from above.

FIG. 4(a) is a cross-sectional view of another electrolytic capacitoraccording to the first embodiment, and FIG. 4(b) is a plan view of thebase plate shown in FIG. 4(a), as viewed from above.

FIG. 5 is a plan view of a base plate of yet another electrolyticcapacitor according to the first embodiment, as viewed from above.

FIG. 6 is a cross-sectional view similar to that shown in FIG. 4(a),showing peripheral fixing portions that communicate with a resin memberof the electrolytic capacitor.

FIGS. 7(a) to 7(d) are plan views similar to those shown in FIGS. 3(b)and 4(b), showing recessed flow channels (groove portions) formed in aresin bonding surface.

FIG. 8 is a cross-sectional view of the electrolytic capacitor, takenalong the line VIII-VIII in FIG. 7(a).

FIG. 9 is a bottom view of a curled portion of a case, as viewed frombelow, showing four slits provided in the curled portion.

FIG. 10 is a cross-sectional view similar to that shown in FIG. 6 ,showing a base plate including a curved surface protruding upward fromthe center thereof toward the periphery thereof.

FIG. 11 is a cross-sectional view similar to that shown in FIG. 6 ,showing a resin injection hole extending through from a resin bondingsurface to a mounting surface.

FIGS. 12(a) to 12(c) are a plan view, a bottom view, and a side viewsimilar to FIGS. 2(a) to 2(c), showing an electrolytic capacitoraccording to a modification of the first embodiment.

FIGS. 13(a) to 13(c) are a plan view, a bottom view, and a side viewsimilar to FIGS. 2(a) to 2(c), showing an electrolytic capacitoraccording to another modification of the first embodiment.

FIG. 14 is a cross-sectional view of the electrolytic capacitor, takenalong the line XIV-XIV in FIG. 13(a).

FIG. 15 is a cross-sectional view of the electrolytic capacitor, takenalong the line XV-XV in FIG. 13(a).

FIG. 16 is a plan view of an electrolytic capacitor according to yetanother modification of the first embodiment.

FIG. 17 is a partial broken-away perspective view partially showing theinterior of an electrolytic capacitor according to a second embodimentof the present invention.

FIG. 18(a) is a cross-sectional view similar to FIG. 3(a), showing theelectrolytic capacitor according to the second embodiment, and FIG.18(b) is a plan view of the base plate shown in FIG. 18(a), as viewedfrom above.

FIG. 19(a) is a cross-sectional view of another electrolytic capacitoraccording to the second embodiment, and FIG. 19(b) is a plan view of thebase plate shown in FIG. 19(a), as viewed from above.

FIG. 20 is a plan view of a base plate of yet another electrolyticcapacitor according to the second embodiment, as viewed from above.

FIG. 21 is a cross-sectional view similar to FIG. 19(a), showingperipheral fixing portions that communicate with a resin member of theelectrolytic capacitor.

FIGS. 22(a) to 22(d) are plan views similar to FIG. 18(b) and FIG.19(b), showing recessed flow channels (groove portions) formed in aresin bonding surface.

FIG. 23 is a cross-sectional view of the electrolytic capacitor, takenalong the line XXIII-XXIII in FIG. 22(a).

FIG. 24 is a cross-sectional view similar to FIG. 23 , showing a baseplate including a curved surface protruding downward from the centerthereof toward the periphery thereof.

FIG. 25 is a cross-sectional view similar to FIG. 21 , showing a resininjection hole extending through from a resin bonding surface through amounting surface.

FIG. 26 is a cross-sectional view of the electrolytic capacitoraccording to the second embodiment, taken along the line XIV-XIV in FIG.13(a).

FIG. 27 is a cross-sectional view of the electrolytic capacitoraccording to the second embodiment, taken along the line XV-XV in FIG.13(a).

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of an electrolytic capacitor according to thepresent invention will be described with reference to the accompanyingdrawings. In the description of the embodiments, terms (e.g., “upper”,“lower”, “outside”, “inside”, etc.) that are used to indicate directionsin order to facilitate the understanding are merely illustrative, andthese terms are not intended to limit the present invention. In thedrawings, constituent parts of the electrolytic capacitor areillustrated in relative dimensions in order to clarify the shape or thecharacteristics thereof, and are not necessarily shown with the samescale ratio.

First Embodiment

FIG. 1 is a partial broken-away perspective view partially showing theinterior of an electrolytic capacitor 1 according to a first embodimentof the present invention. FIGS. 2(a) to 2(c) are a plan view, a bottomview, and a side view, respectively, of the electrolytic capacitor 1shown in FIG. 1 . As schematically shown in FIG. 1 , the electrolyticcapacitor 1 according to the first embodiment includes a capacitorelement 10 including a pair of electrodes 2 (only one electrode 2 isshown in the drawing), an electrolyte (not shown) interposed between thepair of electrodes 2, a case 20 that accommodates the capacitor element10 and the electrolyte and has an opening, a base plate 50 (alsoreferred to as an “insulating plate”) having a pair of through holes 51(FIG. 3 ), a resin member 40 (also referred to as an “adhesivematerial”) filled between the sealing member 30 and the base plate 50,and a pair of leads 60 connected to the pair of electrodes 2 of thecapacitor element 10 and extending from the through holes 51 of the baseplate 50. In addition, the base plate 50 has a resin bonding surface 52that abuts against the resin member 40, and a mounting surface 53opposed thereto, and includes at least one protrusion 70 on the resinbonding surface 52.

Hereinafter, the capacitor element 10, the case 20, the sealing member30, and the leads 60 (electrode 2) that are widely used for theelectrolytic capacitor 1 will be described with reference to theaccompanying drawings. However, the present invention is not limited tothese constituent parts, and other capacitor elements, cases, sealingmembers, and electrodes may be used. Note that the electrolyticcapacitor 1 according to the present invention is also applicable toelectrolytic capacitors that use an electrolytic solution or a solidelectrolyte such as a conductive polymer as the electrolyte, and theso-called hybrid electrolytic capacitor that uses an electrolyticsolution and a solid electrolyte as the electrolyte.

(Capacitor Element)

Referring again to FIG. 1 , the capacitor element 10 will be described.The capacitor element 10 is generally formed by winding an anode foil 12having a dielectric layer, a cathode foil 14, and a separator 16 thatretains an electrolyte between the anode foil 12 and the cathode foil14. In addition, the capacitor element 10 includes a pair of electrodes2 (only one electrode 2 is shown in FIG. 1 ) electrically connected tothe anode foil 12 and the cathode foil 14, respectively. The capacitorelement 10 further includes a winding stop tape (not shown) with whichthe outermost layer thereof is fixed.

Although not by way of limitation, the anode foil 12 is formed byroughening the surface of a metal foil made of a valve metal such asaluminum, tantalum, or niobium, or an alloy containing these valvemetals. Surface roughening of the metal foil may be performed using anetching technique such as direct-current electrolysis oralternating-current electrolysis. By roughening the surface of the metalfoil, a plurality of projections and depressions can be formed on thesurface of the metal foil. The dielectric layer on the anode foil 12 isformed along the inner wall surfaces of holes or dents (pits) on theroughened surface, so that the surface area can be increased.

The dielectric layer on the anode foil 12 may be formed, for example, byimmersing the metal foil in a chemical formation solution such as anammonium adipate solution, and subjecting the metal foil (with a voltageapplied thereto, if necessary) to chemical formation treatment. Ingeneral, the anode foil 12 can be mass-produced by roughening thesurface of a large-sized metal foil containing a valve metal or thelike, then subjecting the surface to chemical formation treatment, andthereafter cutting the metal foil to a desired size.

Similarly, the cathode foil 14 is formed by roughening the surface of ametal foil made of a valve metal such as aluminum, tantalum, or niobium,or an alloy containing these valve metals. If necessary, the cathodefoil 14 may be subjected to surface roughening and/or chemical formationtreatment, as in the case of the anode foil 12.

Although not by way of limitation, the separator 16 may be formed, forexample, using a non-woven fabric or the like containing fibers ofcellulose, polyethylene terephthalate, vinylon, polyamide (e.g.,aliphatic polyamide, aromatic polyamide such as aramid).

The capacitor element 10 can be formed, for example, by stacking andwinding the anode foil 12 on which a dielectric layer is formed, theseparator 16, and the cathode foil 14, and causing the separator 16 toretain an electrolyte. The capacitor element 10 shown in FIG. 1 isformed such that ends of the pair of electrodes 2 (only one electrode 2is shown in FIG. 1 ) are electrically connected to the anode foil 12 andthe cathode foil 14, respectively, and the other ends thereof extendfrom an end face (a lower end face in FIG. 1 ) of the capacitor element10.

As the electrolyte, it is possible to use a solid electrolyte, anelectrolytic solution, and a hybrid electrolyte obtained by combining anelectrolytic solution and a solid electrolyte or the like. Theelectrolyte may be a mixture of a non-aqueous solvent and an ionicsubstance (a solute, e.g., an organic salt) dissolved in the non-aqueoussolvent. The non-aqueous solvent may be an organic solvent or an ionicliquid. As the non-aqueous solvent, it is possible to use, for example,ethylene glycol, propylene glycol, sulfolane, γ-butyrolactone,N-methylacetamide and the like. Examples of the organic salt includetrimethylamine maleate, triethylamine borodisalicylate,ethyldimethylamine phthalate, mono 1,2,3,4-tetramethylimidazoliniumphthalate, and mono 1,3-dimethyl-2-ethylimidazolinium phthalate.

The solid electrolyte contains, for example, a manganese compound or aconductive polymer. As the conductive polymer, it is possible to use,for example, polypyrrole, polythiophene, polyaniline, and derivativesthereof. The solid electrolyte containing a conductive polymer can beformed, for example, by subjecting a raw material monomer to chemicalpolymerization and/or electrolysis polymerization on the dielectriclayer. Alternatively, the solid electrolyte can be formed by applying,to a dielectric layer, a solution in which a conductive polymer isdissolved, or a dispersion in which a conductive polymer is dispersed.Note that the capacitor element is not limited to those described above,and may have any configuration as long as it serves the function of acapacitor element

(Sealing Member)

The sealing member 30 can be formed using any insulating material, butis preferably formed using a rubber member having high elasticity andhigh sealing performance. In addition, examples of a rubber memberhaving high heat resistance include silicone rubber, fluorine rubber,ethylene propylene rubber, chlorosulfonated polyethylene rubber (Hypalonrubber, etc.), butyl rubber, and isoprene rubber.

The sealing member 30 has a planar shape (e.g., a circular plate-shapeor a disc shape) corresponding to the shape of the opening of the case20, and is molded in advance so as to have insertion holes (not shown)for passing the tab portions 19 of the electrodes 2 therethrough.

(Electrodes)

Each of the pair of electrodes 2 has a tab portion 19 extending from thecapacitor element 10, and a pair of leads 60 are connected to the tabportions 19 inside the sealing member 30 by welding or the like.Preferably, the tab portions 19 are formed of, for example, a valvemetal such as aluminum, and is covered with an oxide film of that metal.On the other hand, the leads 60 are formed of, for example, a CP wire, aCu wire or the like that contains a transition metal such as iron,copper, nickel, and tin. Although a portion of each of the tab portions19 and each of the leads 60 is embedded in the sealing member 30, thediameter of the leads 60 is smaller than the diameter of the tabportions 19, and, therefore, an annular space 32 is formed around eachof the leads 60 in the sealing member 30.

(Case)

Typically, the case 20 has a substantially cylindrical shape, and has anopening that accommodates the capacitor element 10 and the sealingmember 30. The case 20 having a substantially cylindrical shape has aside portion 21, and a substantially annular drawn portion 23 and acurled portion 25 that extend continuously with the side portion 21.That is, the curled portion 25 defines the opening of the case 20. Thecase 20 is formed using, for example, a metal such as aluminum,stainless steel, copper, iron, and brass, or alloys thereof. Note thatthe side portion 21, the drawn portion 23, and the curled portion 25 ofthe case 20 may be partially or entirely covered by a laminate film, ormay not be covered thereby. The necessity for a covering of a laminatefilm and the material of the laminate film may be determined based ondetermining the adhesion compatibility with a resin member 40, whichwill be described below.

(Resin Member, Adhesive Material)

The electrolytic capacitor 1 according to an embodiment of the presentinvention includes a resin member 40 filled between the sealing member30 and a base plate 50, which will be described below. FIG. 3(a) is across-sectional view of the electrolytic capacitor 1, taken along theline III-III in FIG. 2(a). As shown in FIG. 3(a), in the electrolyticcapacitor 1, the capacitor element 10 and the sealing member 30 areaccommodated in the case 20. Then, in a state in which the electrolyticcapacitor 1 is vertically inverted from the state shown in FIG. 3(a),uncured fluid resin is filled in a space defined by the surface of thesealing member 30, the inner surface of the case 20 and the resinbonding surface 52 of the base plate 50, and the annular spaces 32formed around the leads 60 so as to seal these spaces in a liquid-tightmanner, thereby forming a resin member 40.

In general, a liquid in the electrolytic capacitor 1 such as theelectrolytic solution may be vaporized, for example, as a result ofreflowing under severe conditions or a long-term use under ahigh-temperature environment, and the vaporized gas may increase theinternal pressure of the case 20, resulting in a stress applied to thesealing member 30. When the internal pressure of the case 20 isincreased, the electrolytic solution may infiltrate (permeate) into thesealing member 30, or may reach the resin member 40 via the spacebetween the sealing member 30 and the tab portions 19 of the electrodes2, or minute voids formed in the interface between the sealing member 30and the case 20. Then, if the electrolytic solution is evaporated anddiffused to the outside of the case 20, the electrolytic capacitor 1 isno longer able to maintain its predetermined properties.

However, according to the first embodiment of the present invention, theresin member 40 is fixed so as to adhere to the case 20 and the baseplate 50 by providing the base plate 50 with the protrusion 70.Accordingly, even if a liquid such as an electrolytic solution isevaporated in the case 20, and infiltrates (permeates) into the sealingmember 30 or reaches the resin member 40 via minutes voids, the resinmember 40 can substantially suppress or prevent evaporation anddiffusion of the electrolytic solution from the inside to the outside ofthe case 20, thus making it possible to maintain the desired reliabilityof the electrolytic capacitor 1.

That is, as described in [Technical Problem] above, the protrusion 70according to the first embodiment of the present invention enhances theadhesion (sealing performance) between the resin member 40 (adhesivematerial) and each of the case 20 and the sealing member 30 bylengthening an entry path of air or the like entering the case 20 fromthe outside and an evaporation-diffusion path of a liquid, such as theelectrolytic solution in the case 20, being evaporated and diffused tothe outside, and making these paths intricate (circuitous), thusrealizing the desired long-term reliability of the electrolyticcapacitor 1.

The resin member 40 according to the first embodiment of the presentinvention is filled so as to seal the annular spaces 32 formed aroundthe leads 60 in a liquid-tight manner. Accordingly, even if theelectrolytic solution reaches the interface between the sealing member30 and the resin member 40, or the annular space 32, it is possible toprevent corrosion of the leads 60 formed of a material containing atransition metal.

Next, the production processes performed before and after filling theresin member 40 will be described more specifically. After the capacitorelement 10 and the sealing member 30 have been accommodated in the case20, a portion near the opening end of the side portion 21 of the case 20is drawn (deformed by pressure applied thereto from the circumferentialdirection), to form a drawn portion 23, and the case 20 is sealed by thesealing member 30. Additionally, the opening end of the case 20 iscurled (the opening end is deformed inward in the radial direction) toform a U-shaped or L-shaped curled portion 25. That is, the drawnportion 23 and the curled portion 25 of the case 20 are formed so as tobe continuous with the side portion 21.

Then, in the case 20 that has been subjected to curling, uncured fluidresin is potted, applied or injected onto the sealing member 30, and,thereafter, the base plate 50 is disposed, with the leads 60 beingpassed through the through holes 51. At this time, the curled portion 25abuts against a portion (referred to as a “reference surface 54” in thepresent application), on which the protrusion 70 is not formed, of theresin bonding surface 52 of the base plate 50, whereby the case 20 isaligned with the base plate 50 in the vertical direction (heightdirection). Thereafter, the fluid resin is cured, thereby forming aresin member 40 filled between the sealing member 30 and the base plate50. Additionally, after the resin member 40 has been formed by curingthe fluid resin, the leads 60 are bent so as to extend along themounting surface 53 of the base plate 50.

Preferably, the fluid resin is thermosetting or photo-curable. The fluidresin may contain a filler, a curing agent, a polymerization initiator,and/or a catalyst. The thermosetting fluid resin may contain, forexample, epoxy resin, phenol resin, urea resin, polyimide, polyamideimide, polyurethane, diallyl phthalate, or an unsaturated polyester. Thefiller may contain, for example, one or more insulating compounds(oxide, etc.) such as silica and alumina, or one or more types ofinsulating particles of glass, a mineral material (talc, mica, clay,etc.) or the like.

The fluid resin may be, or may contain, for example, a thermoplasticresin such as polyphenylene sulfide (PPS) or polybutylene terephthalate(PBT). Additionally, the fluid resin may be injected using a moldingtechnique such as injection molding, insert molding or compressionmolding.

(Base Plate, Insulating Plate)

FIG. 3(b) is a plan view of the base plate 50 shown in FIG. 3(a), asviewed from above. FIG. 4(a) is a cross-sectional view of anotherelectrolytic capacitor 1 according to the first embodiment, and FIG.4(b) is a plan view of the base plate 50 shown in FIG. 4(a), as viewedfrom above. FIG. 5 is a plan view of a base plate 50 of yet anotherelectrolytic capacitor 1 according to the first embodiment, as viewedfrom above. In the drawings, a set of points (i.e., a circle) at whichthe curled portion 25 of the case 20 abuts against the reference surface54 of the base plate 50 is indicated by the dashed line.

As shown in FIGS. 3(b) and 4(b), the base plate 50 according to theembodiment of the present invention, in its simplest form, has asubstantially square planar shape, and includes two cut-out portions 55for indicating the polarities. In addition, the base plate 50 has aresin bonding surface 52 (upper surface) that abuts against the resinmember 40, and a mounting surface 53 (lower surface) opposed to amounting substrate (not shown), and includes at least one protrusion 70on the resin bonding surface 52. The protrusion 70 may be a singleprotrusion formed concentrically with the center of the case as shown inFIG. 3(b), or may include two protrusions 70 as shown in FIG. 4(b).Alternatively, the protrusion 70 may be a combination of a protrusion 70disposed near the center and protrusions 70 extending radially (in theradial direction), as shown in FIG. 5 . Further, a larger number ofprotrusions 70 may be provided, or a grid-shaped or zigzag-shapedprotrusion 70 (not shown) may be provided.

When the electrolytic capacitor 1 is subjected to a significant changein ambient temperature (thermal shock) during use, the sealing member 30tends to significantly expand or contract relative to the resin member40, due to the difference in coefficient of thermal expansion betweenthe sealing member 30 and the resin member 40. However, according to thefirst embodiment of the present invention, by providing the resinbonding surface 52 with the protrusion 70, it is possible tosubstantially increase the adhesion strength between the sealing member30 and the resin member 40 to reliably block air (oxygen) and/or water(water vapor) entering from the outside, and to substantially suppressor prevent evaporation and diffusion (reduction) of a liquid such as anelectrolytic solution to the outside of the case 20, thus ensuring thedesired long-term reliability of the electrolytic capacitor 1.

Although not illustrated in detail, an inclined portion or a curvedportion (not shown) may be provided near each of the through holes 51 ofthe base plate 50, in order to reduce the stress applied to the leads 60when the leads 60 are bent after the resin member 40 has been cured.Since the through holes 51 of the base plate 50 are formed in theprotrusion 70, the inclined portion or the curved portion can be easilyformed as compared with a case where no protrusion is formed as in theconventional techniques.

Furthermore, the resin member 40 according to an embodiment of thepresent invention preferably includes, as shown in FIG. 6 , peripheralfixing portions 42 extending from the curled portion 25 toward the drawnportion 23, and configured to restrict or fix the case 20 from theoutside by being bonded to at least a portion of the outer surface ofthe case 20 (the detailed description will be given later). Accordingly,the adhesion strength between the resin member 40 and each of the baseplate 50 and the case 20 is further improved, so that it is possible tomore reliably achieve the blocking of air or the like entering from theoutside, and the prevention of evaporation and diffusion of anelectrolytic solution or the like to the outside, thus realizing higherreliability of the electrolytic capacitor 1.

(Peripheral Fixing Portion)

As described above, the portion (FIG. 6 ) of the resin member 40 thatfixes the case 20 from the outside is referred to as a peripheral fixingportion 42 in the present application, for the sake of the convenience.Preferably, the peripheral fixing portion 42 is integrated in one piecewith the resin member 40 filled between the sealing member 30 and thebase plate 50, or in other words, in communication (continuous) with theresin member 40. The peripheral fixing portion 42 can be easily formedby providing a flow channel through which uncured fluid resin forforming the resin member 40 flows to the outside of the case 20.

Next, the configuration of the base plate 50 or the curled portion 25 ofthe case 20 for forming the peripheral fixing portions 42 will bedescribed with reference to FIGS. 7 to 11 . FIGS. 7(a) to 7(d) are planviews of a base plate 50 obtained by forming recessed flow channels 56(groove portions) in the reference surface 54 of the resin bondingsurface 52 of the base plate 50 shown in FIGS. 3(b) and 4(b). In thedrawings, the recessed flow channels 56 are hatched, and a set of points(i.e., a dashed circle) at which the curled portion 25 of the case 20abuts against the reference surface 54 of the base plate 50 is indicatedby the dashed line, for the sake of convenience.

In each of the cases, the curled portion 25 of the case 20 abuts againstthe reference surface 54 of the resin bonding surface 52 of the baseplate 50, and therefore, the position of the case 20 relative to thebase plate 50 in the vertical direction (height direction) is restricted(aligned). Uncured fluid resin having viscosity is potted or injectedonto the sealing member 30 in a state in which the case 20 is verticallyinverted. Thereafter, when the base plate 50 is pressed downward with apredetermined pressure, the fluid resin is filled in the space betweenthe sealing member 30 and each of the reference surface 54 of the resinbonding surface 52 of the base plate 50, the protrusion 70, and therecessed flow channels 56 (FIG. 7 ), and in the annular spaces 32 aroundthe leads 60.

At this time, the excess fluid resin is extruded to the outside of thecase 20 via the recessed flow channels 56, and flows along the outersurface of the case 20. That is, the recessed flow channels 56 providecommunication between the fluid resins located inside and outside thecurled portion 25. Note that it is preferable to prevent entry of airbubbles into the space between the sealing member 30 and the base plate50 when the base plate 50 is pressed downward. However, the presentinvention does not require complete prevention of entry of air bubbles,and allows entry of air bubbles to a certain degree. When the fluidresin filled and extruded in this manner has been cured, the resinmember 40 and the peripheral fixing portions 42 are formed as a singlepiece.

The fluid resin covers the entire circumference of the curled portion25, and the curled portion 25 (in particular, an end thereof) isdisposed so as to be spaced apart from the sealing member 30. Inparticular, when the curled portion 25 has an U-shape, the fluid resinis filled so as to abut against the upper surface and the lower surfaceof the curled portion 25 including a curved surface protruding downward,and to abut against the inner surface and the outer surface of thedistal end of the curled portion 25 extending in a direction along theresin bonding surface 52 (i.e., the fluid resin is bonded so as tosurround the curled portion 25 from above, below, the left and theright), so that the resin member 40 can more firmly fix the curledportion 25.

It should be noted that the distal end of the curled portion of PTL 2described above sticks into the sealing member, and the lower surface ofthe curled portion is merely bonded to the resin layer, without anyresin layer formed on the upper surface of the curled portion.Therefore, the bonding strength between the curled portion and the resinlayer is very low.

The recessed flow channels 56 shown in FIGS. 7(a) and 7(b) extend towardcorner portions 57 of the base plate 50, and the peripheral fixingportions 42 are formed near the corner portions 57 of the base plate 50.The recessed flow channels 56 shown in FIGS. 7(c) and 7(d) extend towardend portions 58 of the base plate 50, and the peripheral fixing portions42 are formed near the end portions 58 of the base plate 50. Note thatFIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG.7(a), showing the recessed flow channels 56 extending toward the cornerportions 57 of the base plate 50.

The planar dimensions of the base plate 50 are specified by the userspecification or a standard specification, and the peripheral fixingportions 42 formed near the corner portion 57 can be formed larger thanthe peripheral fixing portions 42 formed near the end portion 58.Therefore, the former is more advantageous than the latter in terms ofenhancement of the adhesion between the resin member 40 and each of thebase plate 50 and the case 20.

Note that the number of the recessed flow channels 56 may be three orless, or may be five or more. The planar shape of the recessed flowchannels 56 may be either larger or smaller than that shown in thedrawings. Additionally, the recessed flow channels 56 are not limited tothose extending toward the corner portions 57 or the end portions 58,but may extend toward an intermediate position between the cornerportion 57 and the end portion 58, and may not necessarily beequidistantly disposed in the circumferential direction.

FIG. 9 is a bottom view of the curled portion 25 of the case 20, asviewed from below, in which the position at which the base plate 50 isdisposed is indicated by the dashed line. The curled portion 25 has asubstantially annular planar shape, and at least one (four in FIG. 9 )slit 26 is formed therein. The slit 26 of the curled portion 25 providescommunication between the fluid resins located inside and outside thecurled portion 25, as in the case of the recessed flow channels 56 ofthe base plate 50.

The curled portion 25 of the case 20 abuts against the reference surface54 of the resin bonding surface 52 of the base plate 50 at a portionwhere no slit 26 is provided, and therefore, the position of the case 20relative to the base plate 50 in the vertical direction (heightdirection) is restricted (aligned). Similarly, when the base plate 50 ispressed downward with a predetermined pressure after the fluid resin hasbeen potted or injected onto the sealing member 30, the fluid resincovers the entire circumference of the curled portion 25, and is filledin the space between the sealing member 30 and the resin bonding surface52 of the base plate 50, and in the annular spaces 32 around the leads60. The excess fluid resin is extruded to the outside of the case 20 viathe slit 26 of the curled portion 25, and flows along the outer surfaceof the case 20 by the action of gravity. When the fluid resin filled andextruded in this manner has been cured, the resin member 40 and theperipheral fixing portions 42 that are in communication (continuous)with each other are formed as a single piece.

Although not illustrated in detail, the number of the slits 26 of thecurled portion 25 is not limited to four (FIG. 9 ), and may be three orless, or five or more. The slit 26 is not limited to a slit extendingtoward the corner portion 57 of the base plate 50, and may be a slitextending toward the end portion 58, or a slit extending toward anintermediate position between the corner portion 57 and the end portion58, and may not necessarily be equidistantly disposed in thecircumferential direction.

As described above, it is preferable to prevent entry of air bubblesinto the space between the sealing member 30 and the base plate 50 whenthe base plate 50 is pressed downward with a predetermined pressureafter the fluid resin has been potted or injected onto the sealingmember 30. Therefore, as shown in FIG. 10 , the base plate 50 may, whilemaintaining the reference surface 54 of the resin bonding surface 52thereof in a flat state (see FIGS. 7(c) and 7(d)), be configured to havea curved surface on which the protrusion 70 disposed at the center andthe recessed flow channels 56 extend continuously. That is, the resinbonding surface 52 of the base plate 50 may be formed so as to include acurved surface protruding upward from the center thereof toward theperiphery thereof, thereby discharging air bubbles, which may becontained in the fluid resin, from the center to the periphery, andfurther to the outside of the case 20 from the recessed flow channels56.

The fluid resin may be injected using a molding technique such asinjection molding, insert molding or compression molding. As shown inFIG. 11 , the base plate 50 may have a resin injection hole 59 extendingtherethrough from the resin bonding surface 52 to the mounting surface53, for injecting uncured fluid resin into the space between the sealingmember 30 and the base plate 50. One or more resin injection holes 59may be provided. It is preferable that, separately from the resininjection hole 59, the base plate 50 has an exhaust hole (not shown) fordischarging air when injecting the fluid resin, and prevents entry ofair bubbles into the space between the sealing member 30 and the baseplate 50. Upon completion of filling of the fluid resin, the resininjection hole 59 and the exhaust hole are filled with the fluid resin,as in the case of the space between the sealing member 30 and the baseplate 50.

Note that in relation to the cross-sectional views of FIG. 3(a), FIG.4(a) and so forth, it has been described above that the resin member 40is s filled so as to completely adhere to the surface of the sealingmember 30, the inner surface of the case 20, the resin bonding surface52 of the base plate 50, and the leads 60 in the annular spaces 32.However, the present invention is not limited thereto. That is, thepresent invention does not exclude a resin member 40 that is slightlyspaced apart from the above-described constituent parts, as long as thedesired long-term reliability of the electrolytic capacitor 1 issubstantially ensured by providing at least one protrusion 70 on theresin bonding surface 52, thus lengthening an entry path of air or thelike entering the case 20 from the outside and an evaporation-diffusionpath of a liquid, such as the electrolytic solution in the case 20,being evaporated and diffused to the outside, and making these pathsintricate, as described above.

(Modifications of Base Plate (Insulating Plate))

FIGS. 12(a) to 12(c) and FIGS. 13(a) to 13(c) are plan views, bottomviews, and side views, respectively, similar to FIGS. 2(a) to 2(c),showing electrolytic capacitors 1 according to modifications of thefirst embodiment described above. Note that the electrolytic capacitors1 according to the modifications have the same configuration as that ofthe above-described embodiment except that the base plate 50 includeswall portions 80 extending along the case 20. Therefore, descriptions ofredundant configurations have been omitted.

While the base plate 50 of the electrolytic capacitor 1 according to thefirst embodiment described above is generally called a “flat baseplate”, the base plate 50 of the electrolytic capacitor 1 according tothe modification shown in FIGS. 12(a) to 12(c) is also referred to as an“alignment flat base plate” because it includes wall portions 80extending along the curled portion 25 of the case 20, and the wallportions 80 serve to align the case 20 with the base plate 50 in thehorizontal direction. Additionally, the base plate 50 according to themodification shown in FIGS. 13(a) to 13(c) is also referred to as a“vibration-resistant base plate” because it includes vibration-resistantwall portions 80 extending along the side portion 21 and the drawnportion 23 of the case 20 over a longer length, and thevibration-resistant wall portions 80 serve to reliably fix the case 20to the base plate 50 to enhance the vibration resistance. The “alignmentflat base plate” and the “vibration-resistant base plate” both includewall portions 80 on the corner portions 57 of the base plate 50.Accordingly, in the present application, these base plates will behereinafter collectively described and referred to as a“vibration-resistant base plate 50” for the sake of convenience.

Although the detailed description has been omitted, as described abovein the embodiments according to the electrolytic capacitor 1 includingthe flat base plate, the recessed flow channels 56 (groove portions) ofthe base plate 50 and the slit 26 of the curled portion 25 that providecommunication (connection) between the resin member 40 and theperipheral fixing portions 42 can be similarly applied to theelectrolytic capacitor 1 including the vibration-resistant base plate.

FIG. 14 is a cross-sectional view taken along the line XIV-XIV in FIG.13(a), and FIG. 15 is a cross-sectional view taken along the line XV-XVin FIG. 13(a). The vibration-resistant base plate 50 includes wallportions 80 at the corner portions 57, and is configured such that theresin member 40 is filled in a gap 82 formed between the side portion 21(alternatively, the drawn portion 23 or the curled portion 25) of thecase 20 and each of the wall portions 80, as shown in FIG. 15 . Thehigher the wall portions 80 of the vibration-resistant base plate 50,the larger the amount of the fluid resin filled between the case 20 andthe wall portions 80 of the vibration-resistant base plate 50 is, sothat the adhesion strength between the resin member 40 and each of thebase plate 50 and the case 20 can be further increased. Thus, theelectrolytic capacitor 1 including the vibration-resistant base plate 50blocks air or the like entering from the outside, and preventsevaporation and diffusion of an electrolytic solution or the like to theoutside, thus making it possible to realize higher reliability of theelectrolytic capacitor 1. As shown in FIG. 14 , each of the wallportions 80 has a portion having a small distance from the side portion21 of the case 20, thus allowing the alignment between the case 20 andthe vibration-resistant base plate 50 to be performed more accurately.

As described above, in general, the planar dimensions of the base plate50 are specified by the user specification or a standard specification.As shown in FIG. 16 , the diameter of the case 20 may be reduced, or theplanar dimensions of the base plate 50 may be increased. Then, the wallportion 80 may be formed not only on the corner portions 57 of thevibration-resistant base plate 50 but also so as to surround the case20, thus allowing the fluid resin (the resin member 40) to be filled inthe gap 82 provided around the entire circumference of the case 20. Thefluid resin filled in the gap 82 provided around the entirecircumference of the case 20 can further increase the adhesion strengthbetween the resin member 40 and each of the base plate 50 and the case20, as compared with the fluid resin only filled in the gap 82 betweenthe corner portions 57 of the base plate 50 and the case 20. Theelectrolytic capacitor 1 including the vibration-resistant base plate 50configured in this manner can more reliably achieve the blocking of airor the like entering from the outside and the prevention of evaporationand diffusion of an electrolytic solution or the like to the outside,thus realizing higher reliability of the electrolytic capacitor 1.

Second Embodiment

An electrolytic capacitor 1 according to a second embodiment of thepresent invention will be described with reference to FIGS. 17 to 27 .The electrolytic capacitor 1 according to the second embodimentgenerally has the same configuration as that of the first embodiment,except that the base plate 50 includes at least one recess 75 on theresin bonding surface 52, in place of the protrusion 70, and therefore,descriptions of redundant details have been omitted.

FIG. 17 is a partial broken-away perspective view partially showing theinterior of the electrolytic capacitor 1 according to the secondembodiment of the present invention. A plan view, a bottom view, and aside view showing the outer shape of the electrolytic capacitor 1according to the second embodiment are the same as FIGS. 2(a) to 2(c)according to the first embodiment.

A capacitor element 10, a case 20, a sealing member 30, a resin member40, and leads 60 (electrodes 2) that are used for the electrolyticcapacitor 1 according to the second embodiment have the sameconfigurations as those of the first embodiment, and are formed in thesame manner as in the first embodiment.

FIG. 18(a) is a cross-sectional view of the electrolytic capacitor 1according to the second embodiment, similar to FIG. 3(a), and FIG. 18(b)is a plan view of the base plate shown in FIG. 18(a), as viewed fromabove. FIG. 19(a) is a cross-sectional view of another electrolyticcapacitor 1 according to the second embodiment, and FIG. 19(b) is a planview of the base plate 50 shown in FIG. 19(a), as viewed from above.FIG. 20 is a plan view of a base plate 50 of yet another electrolyticcapacitor 1 according to the second embodiment, as viewed from above. Inthe drawings, a set of points (i.e., a circle) at which the curledportion 25 of the case 20 abuts against the reference surface 54 of thebase plate 50 is indicated by the dashed line.

As described above, in the electrolytic capacitors 1 according to thesecond embodiment, the base plate 50 includes at least one recess 75 onthe resin bonding surface 52 (in particular, see FIGS. 17, 18 (a) and19(a)).

That is, according to the second embodiment of the present invention, asin the case of the first embodiment, the resin member 40 is fixed so asto adhere to the case 20 and the base plate 50 by providing the baseplate 50 with the recess 75. Accordingly, even if a liquid such as anelectrolytic solution is evaporated in the case 20, and infiltrates(permeates) into the sealing member 30 or reaches the resin member 40via minutes voids, the resin member 40 can substantially suppress orprevent evaporation and diffusion of the electrolytic solution from theinside to the outside of the case 20. Thus, it is possible to maintainthe desired reliability of the electrolytic capacitor 1.

The recess 75 according to the second embodiment of the presentinvention can enhance the adhesion (sealing performance) between theresin member 40 (adhesive material) and each of the case 20 and thesealing member 30 and can lengthen an entry path of air or the likeentering the case 20 from the outside and an evaporation-diffusion pathof a liquid, such as the electrolytic solution in the case 20, beingevaporated and diffused to the outside, and make these paths intricate(circuitous). Thus, it is possible to realize the desired reliability ofthe electrolytic capacitor 1 over a longer period of time.

Furthermore, the resin member 40 according to the second embodiment isfilled so as to seal the annular spaces 32 formed around the leads 60 ina liquid-tight manner. Accordingly, even if the electrolytic solutionreaches the interface between the sealing member 30 and the resin member40, or the annular space 32, it is possible to prevent corrosion of theleads 60 formed of a material containing a transition metal (see FIGS.18(a) and 19(a)).

The production processes performed before and after filing the resinmember 40, and the specific properties and the constituent materials ofthe fluid resin are the same as those of the first embodiment, andtherefore, the detailed descriptions thereof have been omitted.

As shown in FIG. 18(b) and FIG. 19(b), the base plate 50 (insulatingplate), in its simplest form, has a substantially square planar shape,and includes two cut-out portions 55 for indicating the polarities. Inaddition, the base plate 50 has a resin bonding surface 52 (uppersurface) that abuts against the resin member 40, and a mounting surface53 (lower surface) opposed to a mounting substrate (not shown), andincludes at least one recess 75 on the resin bonding surface 52. Therecess 75 may have a circular planar shape formed concentrically withthe center of the case as shown in FIG. 18(b), or may have a toroidalplanar shape as shown in FIG. 19(b). Alternatively, the recess 75 may bea combination of a recess 75 disposed near the center and recesses 75extending radially (in the radial direction), as shown in FIG. 20 .Further, a larger number of recesses 75 may be provided, or agrid-shaped or zigzag-shaped recess 75 (not shown) may be provided.

When the electrolytic capacitor 1 is subjected to a significant changein ambient temperature (thermal shock) during use, the sealing member 30tends to significantly expand or contract relative to the resin member40, due to the difference in coefficient of thermal expansion betweenthe sealing member 30 and the resin member 40. However, according to thesecond embodiment of the present invention, by providing the resinbonding surface 52 with the recess 75, it is possible to substantiallyincrease the adhesion strength between the sealing member 30 and theresin member 40 to reliably block air (oxygen) and/or water (watervapor) entering from the outside, and to substantially suppress orprevent evaporation and diffusion (reduction) of a liquid such as anelectrolytic solution to the outside of the case 20, thus ensuring thedesired long-term reliability of the electrolytic capacitor 1.

Furthermore, the resin member 40 according to the second embodiment ofthe present invention preferably includes, as shown in FIG. 21 ,peripheral fixing portions 42 extending from the curled portion 25toward the drawn portion 23, and configured to restrict or fix the case20 from the outside by being bonded to at least a portion of the outersurface of the case 20. Accordingly, the adhesion strength between theresin member 40 and each of the base plate 50 and the case 20 is furtherimproved, so that it is possible to more reliably achieve the blockingof air or the like entering from the outside, and the prevention ofevaporation and diffusion of an electrolytic solution or the like to theoutside, thus realizing higher reliability of the electrolytic capacitor1.

FIGS. 22(a) to 22(d) are plan views of a base plate 50 obtained byforming recessed flow channels 56 (groove portions) in the referencesurface 54 of the resin bonding surface 52 of the base plate 50 shown inFIGS. 18(b) and 19(b). In the drawings, the recessed flow channels 56are hatched, and a set of points (i.e., a dashed circle) at which thecurled portion 25 of the case 20 abuts against the reference surface 54of the base plate 50 is indicated by the dashed line, for the sake ofconvenience.

The recessed flow channels 56 shown in FIGS. 22(a) and 22(b) extendtoward the corner portions 57 of the base plate 50, and the peripheralfixing portions 42 are formed near the corner portions 57 of the baseplate 50. The recessed flow channels 56 shown in FIGS. 22(c) and 22(d)extend toward the end portions 58 of the base plate 50, and theperipheral fixing portions 42 are formed near the end portions 58 of thebase plate 50. Note that FIG. 23 is a cross-sectional view taken alongthe line XXIII-XXIII in FIG. 22(a), showing the recessed flow channels56 extending toward the corner portions 57 of the base plate 50.

Although the recessed flow channels 56 shown in FIG. 23 are illustratedas having the same depth as the recess 75 formed in the base plate 50 onthe inner side of the curled portion 25, the recessed flow channels 56are not limited thereto, and may be formed so as to be deeper orshallower than the recess 75.

The configurations of the peripheral fixing portions 42, the recessedflow channels 56, and the slit 26, and the method for forming theperipheral fixing portions 42 are similar to those described in thefirst embodiment, and therefore, further descriptions of redundantdetails have been omitted.

Note that it is preferable to prevent entry of air bubbles into thespace between the sealing member 30 and the base plate 50 when the baseplate 50 is pressed downward with a predetermined pressure after thefluid resin has been potted or injected onto the sealing member 30.Since the base plate 50 shown in FIG. 24 is configured to include acurved surface protruding downward from the center thereof to theperiphery thereof, air bubbles, which may be contained in the fluidresin, are discharged from the center to the periphery, and further tothe outside of the case 20 from the recessed flow channels 56.

As shown in FIG. 25 , the base plate 50 may have a resin injection hole59 extending therethrough from the resin bonding surface 52 to themounting surface 53 for injecting uncured fluid resin into the spacebetween the sealing member 30 and the base plate 50. One or more resininjection holes 59 may be provided. It is preferable that, separatelyfrom the resin injection hole 59, the base plate 50 has an exhaust hole(not shown) for discharging air when injecting the fluid resin, andprevents entry of air bubbles into the space between the sealing member30 and the base plate 50. Upon completion of filling of the fluid resin,the resin injection hole 59 and the exhaust hole are filled with thefluid resin, as in the case of the space between the sealing member 30and the base plate 50.

Although not illustrated in detail here, the modifications describedwith reference to the FIGS. 12(a) to 12(c), FIGS. 13(a) to 13(c) andFIGS. 14 to 16 for the vibration-resistant base plate 50 (insulatingplate) according to the first embodiment can be similarly applied to thesecond embodiment (the vibration-resistant base plate 50 including therecess 75).

FIGS. 26 and 27 are cross-sectional views of an electrolytic capacitoraccording to the second embodiment, taken along the line XIV-XIV and theline XV-XV, respectively, in FIG. 13(a). The vibration-resistant baseplate 50 includes wall portions 80 at the corner portions 57, and isconfigured such that the resin member 40 is filled in a gap 82 formedbetween the side portion 21 (alternatively, the drawn portion 23 or thecurled portion 25) of the case 20 and each of the wall portions 80, asshown in FIG. 27 . The higher the wall portions 80 of thevibration-resistant base plate 50, the larger the amount of the fluidresin filled between the case 20 and the wall portions 80 of thevibration-resistant base plate 50 is, so that the adhesion strengthbetween the resin member 40 and each of the base plate 50 and the case20 can be further increased. Thus, the electrolytic capacitor 1including the vibration-resistant base plate 50 blocks air or the likeentering from the outside, and prevents evaporation and diffusion of anelectrolytic solution or the like to the outside, thus making itpossible to realize higher reliability of the electrolytic capacitor 1.As shown in FIG. 26 , each of the wall portions 80 has a portion havinga small distance from the side portion 21 of the case 20, thus allowingthe alignment between the case 20 and the vibration-resistant base plate50 to be performed more accurately.

INDUSTRIAL APPLICABILITY

The present invention is applicable to an electrolytic capacitorincluding a resin member filled between a sealing member and a baseplate.

REFERENCE SIGNS LIST

-   -   1 . . . Electrolytic capacitor    -   2 . . . Electrode    -   10 . . . Capacitor element    -   12 . . . Anode foil    -   14 . . . Cathode foil    -   16 . . . Separator    -   19 . . . Tab portion    -   20 . . . Case    -   21 . . . Side portion    -   23 . . . drawn portion    -   25 . . . Curled portion    -   26 . . . Slit    -   30 . . . Sealing member    -   32 . . . Annular space    -   40 . . . Resin member (adhesive material)    -   42 . . . Peripheral fixing portion    -   50 . . . Base plate (insulating plate)    -   51 . . . Through hole    -   52 . . . Resin bonding surface    -   53 . . . Mounting surface    -   54 . . . Reference surface    -   55 . . . Cut-out portion    -   56 . . . Recessed flow channel (groove portion)    -   57 . . . Corner portion    -   58 . . . End portion    -   59 . . . Resin injection hole    -   60 . . . Lead    -   70 . . . Protrusion    -   75 . . . Recess    -   80 . . . Wall portion    -   82 . . . Gap

The invention claimed is:
 1. An electrolytic capacitor comprising: acapacitor element including a pair of electrodes; an electrolyteinterposed between the pair of electrodes; a pair of leads electricallyconnected to the pair of electrodes, respectively; a case in which thecapacitor element and the electrolyte are accommodated, and that has anopening; a sealing member that seals the opening, and has a pair ofinsertion holes for leading out the leads; an insulating plate having apair of through holes for leading out the leads; and a resin memberfilled between the sealing member and the insulating plate, wherein: theinsulating plate has a resin bonding surface that abuts against theresin member, and a mounting surface opposed to the resin bondingsurface, and includes a protrusion on the resin bonding surface, theprotrusion is at least a combination of a plurality of protrudingportions extending radially, the case includes a curled portionincluding the opening, the plurality of protruding portions have atleast one groove portion disposed below at least a portion of the curledportion on the resin bonding surface, and the resin member filledbetween the sealing member and the insulating plate fills between thecurled portion and the groove portion.
 2. The electrolytic capacitoraccording to claim 1, wherein the case includes a drawn portionextending continuously with the curled portion on the outer surface ofthe case, and a side portion extending continuously with the drawnportion, the insulating plate includes a wall portion extending from theresin bonding surface to the side portion along the outer surface of thecase, and the resin member is configured to cover a portion of the outersurface in a gap formed between the outer surface and the wall portion.3. The electrolytic capacitor according to claim 2, wherein a principalsurface of the insulating plate has a substantially rectangular shape,and the wall portion is disposed at a corner portion of the insulatingplate.
 4. The electrolytic capacitor according to claim 1, wherein anend portion of the curled portion is spaced apart from the sealingmember, and the resin member is filled between the curled portion andthe sealing member.
 5. The electrolytic capacitor according to claim 1,wherein the protrusion of the insulating plate is disposed inward of thecurled portion.
 6. The electrolytic capacitor according to claim 1,wherein at least a portion of the curled portion abuts against the resinbonding surface of the insulating plate.
 7. The electrolytic capacitoraccording to claim 1, wherein each of the electrodes includes a tabportion that is electrically connected to the corresponding lead insidethe sealing member, the sealing member has a pair of annular spacesrespectively formed around the leads having a diameter smaller than thatof the tab portions, and the resin member is filled in the annularspaces.
 8. The electrolytic capacitor according to claim 1, wherein theinsulating plate has a resin injection hole extending therethrough fromthe resin bonding surface to the mounting surface between the pair ofthrough holes.
 9. The electrolytic capacitor according to claim 1,wherein the resin bonding surface of the insulating plate includes acurved surface protruding upward from a center thereof toward aperiphery thereof.
 10. An electrolytic capacitor comprising: a capacitorelement including a pair of electrodes; an electrolyte interposedbetween the pair of electrodes; a pair of leads electrically connectedto the pair of electrodes, respectively; a case in which the capacitorelement and the electrolyte are accommodated, and that has an opening; asealing member that seals the opening, and has a pair of insertion holesfor leading out the leads; an insulating plate having a pair of throughholes for leading out the leads; and a resin member filled between thesealing member and the insulating plate, wherein: the insulating platehas a resin bonding surface that abuts against the resin member, and amounting surface opposed to the resin bonding surface, and includes atleast one a recess on the resin bonding surface, and the recess is atleast a combination of a plurality of recessed portions extendingradially.
 11. The electrolytic capacitor according to claim 10, whereinthe case includes a curled portion including the opening, the pluralityof recessed portions have at least one groove portion disposed below atleast a portion of the curled portion on the resin bonding surface, andthe resin member filled between the sealing member and the insulatingplate fills between the curled portion and the groove portion.
 12. Theelectrolytic capacitor according to claim 10, wherein the case includesa curled portion including the opening, the case includes a drawnportion extending continuously with the curled portion on the outersurface of the case, and a side portion extending continuously with thedrawn portion, the insulating plate includes a wall portion extendingfrom the resin bonding surface to the side portion along the outersurface of the case, and the resin member is configured to cover aportion of the outer surface in a gap formed between the outer surfaceand the wall portion.
 13. The electrolytic capacitor according to claim12, wherein a principal surface of the insulating plate has asubstantially rectangular shape, and the wall portion is disposed at acorner portion of the insulating plate.
 14. The electrolytic capacitoraccording to claim 10, wherein the case includes a curled portionincluding the opening, and an end portion of the curled portion isspaced apart from the sealing member, and the resin member is filledbetween the curled portion and the sealing member.
 15. The electrolyticcapacitor according to claim 10, wherein the case includes a curledportion including the opening, and the recess of the insulating plate isdisposed inward of the curled portion.
 16. The electrolytic capacitoraccording to claim 10, wherein the case includes a curled portionincluding the opening, and at least a portion of the curled portionabuts against the resin bonding surface of the insulating plate.
 17. Theelectrolytic capacitor according to claim 10, wherein each of theelectrodes includes a tab portion that is electrically connected to thecorresponding lead inside the sealing member, the sealing member has apair of annular spaces respectively formed around the leads having adiameter smaller than that of the tab portions, and the resin member isfilled in the annular spaces.
 18. The electrolytic capacitor accordingto claim 10, wherein the insulating plate has a resin injection holeextending therethrough from the resin bonding surface to the mountingsurface between the pair of through holes.
 19. The electrolyticcapacitor according to claim 10, wherein the resin bonding surface ofthe insulating plate includes a curved surface protruding downward froma center thereof toward a periphery thereof.
 20. An electrolyticcapacitor comprising: a capacitor element including a pair ofelectrodes; an electrolyte interposed between the pair of electrodes; apair of leads electrically connected to the pair of electrodes,respectively; a case in which the capacitor element and the electrolyteare accommodated, and that has an opening; a sealing member that sealsthe opening, and has a pair of insertion holes for leading out theleads; an insulating plate having a pair of through holes for leadingout the leads; and a resin member filled between the sealing member andthe insulating plate, wherein: the insulating plate has a resin bondingsurface that abuts against the resin member, and a mounting surfaceopposed to the resin bonding surface, and includes a protrusion on theresin bonding surface, the protrusion is at least a combination of aplurality of protruding portions extending radially, and the insulatingplate has a resin injection hole extending therethrough from the resinbonding surface to the mounting surface between the pair of throughholes.